1. Field of the Invention
The present invention relates to a system and method for improved traffic flow reporting. More particularly, the present invention relates to a system and method utilizing a Satellite Digital Audio Radio Service (SDARS) system and Vehicle Communications, Navigation, and Tracking (VCNT) services for aggregating traffic flow data and broadcasting traffic flow data to vehicles in a manner that conserves system bandwidth and provides timely traffic flow updates.
2. Description of the Related Art
Traffic information services have been deployed that use sensors and communications technologies to notify commuters of traffic conditions and, in some cases, of alternate routes in an effort to reduce traffic congestion. Typically, these traffic information services receive traffic update data from such sources as private commercial services, police and emergency services, departments of transportation, roadway cameras and airborne reports. However, these updates are usually outdated by the time they are transmitted to commuters.
Some Global Positioning System (GPS) vendors offer traffic reporting options on their GPS devices through FM or satellite-radio add-on devices. These GPS devices with add-on traffic features can receive traffic information for a general area and some can calculate alternate routes to avoid problem traffic areas. Some GPS devices can report information from which current speed and location can be obtained. Some traffic aggregation systems can combine this reported information with other data (e.g., data from departments of transportation, policy and emergency services, private and municipal traffic sensors and cameras and airborne visual reports) to develop historical data or traffic patterns based on date and time for use in tables and maps that can be consulted by commuters. These systems, however, are not updated with sufficient frequency to provide real-time data on the actual traffic flow occurring along a given route or along alternate routes. Thus, the result is often inaccurate drive-time estimates.
Another technology developed to improve traffic information service is the RDS (Radio Data System) standard described in the document TMC Compendium, Alert-C Coding Handbook, Version F02.1, Jan. 2, 1999. According to this standard, information about traffic incidents, including their location, can be broadcast on a radio channel. A RDS-equipped receiver can decode all such traffic information and may filter the information based on receiver location, for example, so that only relevant information is presented to the user.
More specifically, the Traffic Message Channel (TMC) is a specific application of the FM Radio Data System (RDS) used for broadcasting real-time traffic and weather information. Data messages comprising traffic event and location codes are received silently and decoded by a RDS-TMC-equipped car radio or navigation system. RDS-TMC receivers use the same list of event codes and a location database of location codes as the TMC traffic information system (TIS) transmitters. These event and location codes can be provided to a memory device for access by a processor in RDS-TMC receivers by way of a navigation system map on CD-ROM, DVD or other memory device or via downloading (e.g., during manufacture or subsequent to manufacture). Alert-C is the European standard for language-independent exchange of traffic information via the RDS-TMC channel. The selection and standardization of these traffic event and location codes simplifies and reduces bandwidth needed to collect and report changes in traffic flow along roadways characterized by the location codes.
The objective of RDS-TMC is to broadcast Traffic and Travel Information (TTI) messages as data on FM transmissions using RDS. This allows delivery of traffic information to vehicle operators without the need to interrupt playback of their radio program, which is the opposite of the common practice of inserting spoken traffic messages within the broadcast audio content that is received and played back to vehicle occupants. Thus, TTI messages can be inaudible data that is broadcast in the background of existing FM radio programs.
The limited data transmission capacity of the RDS system does not generally permit implementation of RDS-TMC on all program services of the same broadcaster. Therefore, for an RDS-TMC receiver to function correctly as a radio and allow the end user to freely choose the radio program, the RDS-TMC receiver must have a double tuner to permit one tuner to always be used for radio listening and the other tuner be used for RDS-TMC data collection.
Although the RDS-TMC protocol can simplify the reporting of traffic events to vehicles with RDS-equipped receivers, a need remains for improving real-time reporting of traffic events to the TMC traffic information system (TIS) to improve the quality of the traffic event information in the RDS messages sent to the receivers. In other words, a need exists for real-time traffic event data collection.
Vehicle probes are being developed to improve real-time traffic event data collection. Mobile traffic probes generally operate autonomously to collect traffic-related data and report it to a central TIS. Many challenges, however, exist with using vehicle probes such as the complexity of management and costs associated with increased bandwidth use and storage and processing of the voluminous raw data transmitted from these probes to a TIS.
A need therefore exists for an improved traffic data collection and reporting system that provides national or regional coverage and traffic data that is updated with improved frequency for more real-time reporting to commuters of traffic situations.
A need also exists for an improved traffic data collection and reporting system that leverages both the advantages of using compressed traffic event and location data such as RDS-formatted data and the advantages of an SDARS system, which employs a multiplexed digital stream having many channels for supporting reception of traffic flow information without compromising user selection and enjoyment of received audio programming.
In addition, a need exits for an improved traffic data collection and reporting system that improves use of mobile vehicle probes.